Building webp jni library

The webp support requires a native library (libwebp_jni) and libwebp.jar. The native libraries are added to the tools/adt/idea/ project in adt-ui/lib/libwebp/[platform].

This describes how to build libwebp_jni for each of the platforms. The steps must be repeated for each platform - once for 32 bit and once for 64 bit architectures. Make sure to do a clean build when switching architectures: git clean -dfX.

libwebp.jar is copied directly from <libwebp>/swig/ to adt-ui/lib/

Windows:

1. Install Visual Studio 2015 with the following components:
   • Visual C++ (including all sub components)
   • Universal Windows App Development Tools
   • Git for Windows
2. Open “Git Bash”, clone libwebp and checkout appropriate branch:

   git clone https://chromium.googlesource.com/webm/libwebp
   

3. Open “Developer Command Prompt for VS2015”
4. Make the webp_jni library as per the following commands:

   # For 64 bit arch (not needed for 32 bit arch)
   cd "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC"
   vcvarsall amd64
   
   cd \git\clone\location\libwebp
   # Make libwebp
   nmake /f Makefile.vc CFG=release-static RTLIBCFG=static OBJDIR=output
   # Make jni binding now
   cd swig
   # For 32 bit
   cl /I..\src /I"%JDK%\include" ^
   /I"%JDK%\include\win32" ^
   libwebp_java_wrap.c /MT /LD /Fe:webp_jni.dll ^
   ..\output\release-static\x86\lib\libwebp.lib
   # For 64 bit
   cl /I..\src /I"C:\Program Files (x86)\Java\jdk1.7.0_55\include" ^
   /I"C:\Program Files (x86)\Java\jdk1.7.0_55\include\win32" ^
   libwebp_java_wrap.c /MT /LD /Fe:webp_jni64.dll ^
   ..\output\release-static\x64\lib\libwebp.lib
   

5. Note that unlike mac and linux, windows library is named webp_jni and not libwebp_jni.

Mac/Linux

1. Clone libwebp and checkout appropriate branch:

   git clone https://chromium.googlesource.com/webm/libwebp
   

2. Edit makefile.unix:

   --- a/makefile.unix
   +++ b/makefile.unix
   @@ -14,10 +14,11 @@
    # These flags assume you have libpng, libjpeg, libtiff and libgif installed. If
    # not, either follow the install instructions below or just comment out the next
    # four lines.
   -EXTRA_FLAGS= -DWEBP_HAVE_PNG -DWEBP_HAVE_JPEG -DWEBP_HAVE_TIFF
   -DWEBP_LIBS= -lpng -lz
   -CWEBP_LIBS= $(DWEBP_LIBS) -ljpeg -ltiff
   -GIF_LIBS = -lgif
   +EXTRA_FLAGS= -fPIC -m32
   +#-DWEBP_HAVE_PNG -DWEBP_HAVE_JPEG -DWEBP_HAVE_TIFF
   +#DWEBP_LIBS= -lpng -lz
   +#CWEBP_LIBS= $(DWEBP_LIBS) -ljpeg -ltiff
   +#GIF_LIBS = -lgif
   
    ifeq ($(strip $(shell uname)), Darwin)
      # Work around a problem linking tables marked as common symbols,
   

3. The above diff is for building for 32 bit arch. To build for 64 bit arch, do not add -m32 to EXTRA_FLAGS.
4. Make the libwebp_jni library as per the following commands

   cd /git/clone/location/libwebp
   make -f makefile.unix
   cd swig
   gcc -shared -fPIC -fno-strict-aliasing -O2 \
       -m32 \
       -I/path/to/your/jdk/include \
       -I/path/to/your/jdk/include/[platform] \
       -I../src \
       -L../src \
       libwebp_java_wrap.c \
       -lwebp \
       -o libwebp_jni.[ext]
   

5. When building for 64 bit, use -o libwebp_jni64.[ext] instead and do not specify the -m32 option.
6. The [ext] for linux is so and for mac is dylib.
7. No need to build the 32 bit variant for mac.